The following reaction mechanism has been proposed for a reaction:
(slow) NO2 + NO2-> NO3 + NO
(fast) NO3 + CO -> CO2 + NO2
A. Write the equation for the overall reaction from the mechanism above.
B.Write the rate law for the reaction
Sum the two equations. NO2 cancels on each side, NO3 cancels on each side to leave
NO2 + CO ==> CO2 + NO
B. The rate law for the reaction is determined by the slow step; therefore,
rate = k(NO2)2
A. The overall reaction can be obtained by summing up the individual steps of the mechanism:
2NO2 + NO2 -> 2NO3 (Step 1)
NO3 + CO -> CO2 + NO2 (Step 2)
By canceling out the NO2 on both sides, the overall reaction can be written as:
2NO2 + CO -> CO2 + 2NO
B. To write the rate law for the reaction, we need to identify the rate-determining step in the mechanism. In this case, the slow step (Step 1) is the rate-determining step. The rate-determining step is the step that is slower compared to the other step(s) and therefore determines the overall rate of the reaction.
The rate law for the slow step (Step 1) can be determined by looking at the stoichiometry of the reactants and reactants:
rate = k[NO2]^2
The exponent of 2 is derived from the stoichiometric coefficient of NO2 in the slow step.
A. To determine the overall reaction from the given mechanism, we need to cancel out the intermediate species. In this case, the intermediate species is NO because it appears in both the first and second step.
The first step of the mechanism suggests that two molecules of NO2 react to form one molecule of NO3 and one molecule of NO.
The second step of the mechanism suggests that one molecule of NO3 reacts with one molecule of CO to form one molecule of CO2 and one molecule of NO2.
To cancel out the intermediate species NO, we need to double the second step of the mechanism. This will give us two molecules of NO2 and two molecules of NO3. Adding the two steps together, we get:
2NO2 + 2NO3 + CO -> 2NO3 + CO2 + 2NO2
Simplifying the equation, we find the overall reaction:
2NO2 + CO -> CO2 + 2NO
B. The rate law for the reaction can be determined by examining the slowest step in the mechanism, which is the first step:
NO2 + NO2 -> NO3 + NO
The stoichiometry of this reaction implies that the rate of the reaction is dependent on the concentration of NO2, which is the reactant. Thus, the rate law for the reaction is:
Rate = k[NO2]^2
Where k is the rate constant and [NO2] is the concentration of NO2.